Horizontal support system for ship tanks for low temperature liquefied gas

ABSTRACT

A ship cargo tank support system for a tank with a circular horizontal cross-section which expands and contracts in service having a plurality of spaced-apart support keys mounted on and located around the periphery of the tank in a substantially horizontal arrangement, each support key having a pair of opposing spaced-apart vertical key contact faces positioned at an acute angle to a radius from the tank center to a midpoint between the key contact faces, a plurality of spaced-apart support blocks joined by connecting means to a ship hold, said support blocks being located around the periphery of the tank with a support block opposite each support key, and with each support block having a pair of opposing spaced-apart vertical block contact faces positioned at the same acute angle as the key contact faces and positioned to have a block contact face in mating contact with a key contact face, whereby upon expansion and contraction of the tank with temperature change uniform horizontal slidable support contact is maintained between mating key contact and block contact faces.

Elited States Patent [1 1 Kircik et al.

[ 1 Oct. 15,1974

1 1 HORIZONTAL SUPPORT SYSTEM FOR SHIP TANKS FOR LOW TEMPERATURE LIQUEFIED GAS [75] Inventors: Willis James Kircik; Elmer Weyman Rothrock, both of Hinsdale; Paul Richard Johnson, Oak Lawn, all of 111.

[73] Assignee: Chicago Bridge & Iron Company, Oak Brook, Ill.

22 Filed: Apr. 12,1973

211 Appl. No.: 350,355

[52] US. Cl 114/74 R, 248/DIG. 1, 248/146 [51] Int. Cl B63b 25/08 [58] Field of Search 114/74, 72, 75; IDS/358462; 248/D1G. l, 146; 62/45, 55; 220/9 LG, 15

[56] References Cited UNITED STATES PATENTS 3,280,778 10/1966 Leathard 114/74 A 3,380,611 4/1968 Brougham et a1. 220/15 3,428,205 2/1969 Basile et al'. 114/74 A 3,583,351 6/1971 Gorman 114/74 A 3.583.352 6/1971 Alleaume 114/74 A 3,680,323 8/1972 Bognacs .v 1 14/74 A 3,712,257 1/1973 Alleaume 114/74 A FOREIGN PATENTS OR APPLICATIONS 1,050,532 10/1954 Germany 248/146 Attorney, Agent, or Firm-Merriam. Marshall, Shapiro & Klose [5 7] ABSTRACT A ship cargo tank support system for a tank with a circular horizontal cross-section which expands and contracts in service having a plurality of spaced-apart support keys mounted on and located around the periphery of the tank in a substantially horizontal arrangement, each support key having a pair of opposing spaced-apart vertical key contact faces positioned at an acute angle to a radius from the tank center to a midpoint between the key contact faces, a plurality of spaced-apart support blocks joined by I connecting means to a ship hold, said support blocks being located around the periphery of the tank with a support block opposite each support key, and with each support block having a pair of opposing spaced-apart vertical block contact faces positioned at the same acute angle as the key contact faces and positioned to have a block contact face in mating contact with a key contact face, whereby upon expansion and contraction of the tank with temperature change uniform horizontal slidable support contact is maintained between mating key contact and block contact faces.

14 Claims, 7 Drawing Figures HORIZONTAL SUPPORT SYSTEM FOR SHIP TANKS FOR LOW TEMPERATURE LIQUEFIED GAS This invention relates to cargo ships. More particularly, this invention is concerned with a support system for a storage tank in a ship which securely holds the storage tank in position yet permits horizontal and vertical dimensional change of the tank with change in temperature, such as due to a product stored therein at a temperature substantially above or below ambient temperature.

Cargo ships have been used for many years to transport liquid materials, and particularly oil, gasoline and other such products. Until recently, most of the liquid materials have been transported in ships at ambient temperature. The support systems used for ship tanks for transporting a liquid at ambient temperature did not present a difficult problem since no unreasonable dimensional changes resulted in either the tanks or the ship hull.

Within the last few years or so it has become quite common to transport refrigerated liquid cargoes in tanks mounted in ships. The tanks used for transporting refrigerated liquid cargoes expand and contract as they are raised from a low temperature to ambient temperature and then lowered to the refrigeration temperature used in transporting a refrigerated liquid. The contraction and expansion of the tank must be accommodated to prevent stresses from developing which lead to failure of the tank or the surrounding ship structure. Not only must the contraction and expansion of the tank be accommodated but, in addition, the tank must be firmly supported in the ship so that it is not torn loose or cracked through the action of sea conditions which a ship can be expected to meet during a voyage. The support system must be capable of transmitting the horizontal (parallel to the ship deck) and vertical (normal to the ship deck) forces to the ship structure. It is also important for some uses that the tank support system faces. In cooperation with the support keys, the system employs a plurality of spaced-apart support blocks joined by connecting means to a ship hold, said support insulate against undue heat transfer from the ship hold to the tank wall.

According to the present invention there is provided an improved tank support system for mounting a tank in a ship so that the tank can freely contract and expand through the dimensional range induced by temperature changes in the tank, such as when the tank is at ambient temperature and then is filled with a refrigerated liquid, such as a cryogenic liquid like liquefied natural gas, or with a heated liquid, for transport to a destination. The invention provides improvements in a ship having a cargo tank, particularly a cargo tank which has a circular horizontal cross-section such as is present in cargo tanks which are substantially spherical or which have a cylindrical wall and a spherical or an eliptical bottom and/or top. The shape of such tanks is considered to render them particularly useful for transporting a liquefied gas or other refrigerated liquid, or even heated liquid, in a ship.

The invention furthermore is concerned with an improved tank support system which employs a plurality of spaced-apart support keys mounted on and located around the periphery of a tank in a substantially horizontal arrangement, with each support key having a pair of opposing spaced-apart vertical key contact faces positioned at an acute angle to a radius from the tank center to a mid-point between the key contact blocks being located around the periphery of the tank with a support block mated to each support key. Each support block has a pair of opposing spaced-apart vertical block contact faces positioned at the same acute angle as the key contact faces so as to place a block contact face in mating contact with a key contact face, whereby upon expansion and contraction of the tank with temperature change uniform horizontal slidable support contact is maintained between mating key contact and block contact faces.

A ship cargo tank is generally mounted so that at least a substantial part of it is located below deck in a ship hold. To retard heat-leak between a refrigerated liquid product in the tank and the ship hold it is conventional to insulate either the tank wall or the ship hold wall. The subject invention can be employed with either of these insulation systems. When the tank wall is to be insulated, it is advisable to insulate the key contact faces, of the key support, from the tank wall. Of course, the key contact faces can be insulated from the tank wall whether or not the tank wallis insulated. Similarly, the block contact faces of the block support can be insulated from the ship hold wall when the hold wall is insulated to retard heat-leak between the tank and the ship hold wall.

The invention will be discussed further in conjunction with the attached drawings, in which:

FIG. 1 is an isometric view of a cargo ship having a plurality of spherical cargo tanks mounted thereon for transporting a refrigerated liquid such as liquefied natural gas;

FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1 and shows one of a plurality of column supports for the cargo tank; 1

FIG. 3 is a horizontal sectional view through the tank of FIG. 2 and illustrates the circumferential placemen of the supporting columns around the tank;

FIG. 4 is a partial front elevational view of the column supporting system for the tank shown in FIGS. 2 and 3;

FIG. 5 is a sectional view taken along the line 5-5 of FIG. 4;

FIG. 6-is a partial front elevational view of another embodiment of tank supporting system; and

FIG. 7 is a sectional view taken along the line 77 of FIG. 6.

So far as is practical the same parts or elements which appear in the different views will be identified by the same numbers.

The cargo ship 10 shown in FIG. 1 has five spherical cargo tanks 11 for transporting a refrigerated liquid such as liquefied natural gas. Each tank 11 is supported by a plurality of columns 12, which in the specific structure shown in FIGS. 2 and 3 has 36 columns. Each column 12 has a vertically positioned I-beam 13 (FIGS. 4 and 5) mounted on a pedestal 14 which is suitably positioned on a supporting base 15 of the ship hold. The I-beam 13 has a web l6 and flanges I7 and 18. The top of each column 12 is reinforced by vertically positioned thicker plates 19 and 20 which are joined at their upper ends to horizontally positioned ring 21. Plates 28 and 29 brace plates 19 and 20. Ring 21 is welded to the tank 11. Extending vertically upright from the top surface of horizontal ring 21 are plates 22 and 23 which ring 24 which is also welded to the outside surface of tank 1 1.

Metal plate 25A is welded to the outside surface of vertical plate 20 and metal plate 25B is mounted to the outside surface of metal plate 19 as shown in FIGS. 4 and 5. The two plates 25A and 2513 together constitute a single support key. Plate 25A has a vertically positioned key contact face 26A and plate 25B has a vertically positioned key contact face 268. Each of the columns 12 positioned around the periphery of tank 11 is provided with a support key of the type just described; thus, there is a plurality of spaced-apart support keys mounted on and located around the periphery of the tank in a substantially horizontally arrangement. In addition, each of the support keys thus has a pair of opposing spaced-apart vertical key contact faces.

Each of the key contact faces 26A and 26B is positioned at an acute angle X (FIG. to a radius from the tank center to a mid-point Z located halfway between the key contact faces 26A and 268. The acute angle X of the key contact faces is precalculated, taking into account the material from which the tank is made and the temperature range through which it is to be subjectedin use, to be an angle which will allow all points on the key contact faces to move in the same plane at all times during expansion and contraction of the tank.

As shown in FIG. 5, the ship hold wall 30 is provided with a recessed space 31 having a rear wall 32 and side walls 33 and 34 vertically positioned. A column 12 fits into each of the recesses 31.

A bracket composed of side plates 40 and 41, top plate 42 and bottom plate 43, joined to wall 34 supports load bearing insulation block 44 mounted on plate 45. The block 44 can be made of resin impregnated wood or some other suitable load bearing insulating material. Bolts 46 can be used to move the block 44 into contact with plate 25A. The face'47 of insulating block 44 constitutes a vertical block contact face which is positioned at the same acute angle as the key contact face 26A. Chocking material 48 is positioned between wall 34 and insulating block 44 after it has been placed in position.

The two insulating blocks 44 and 51 together constitute a single support block which mates with the support key. Insulating block 51, having block contact face 52, is positioned to mate with the key contact surface 268 of plate 253. Insulating block 51 is mounted on vertical plate 53. The insulating block 51 is held in place by a bracket composed of side plates 54 and 55, bottom plate 57 and top plate 56 all joined to wall 33. Bolts 58 can be used to adjust the block contact face 52 into contact with the key contact face 268 of plate 253 after which chocking material 59 can be placed in the space between plates 53 and 33.

The embodiment described in detail with respect to FIGS. 4 and 5 is employed when it is considered advisable to leave the external surface of the tank located in a ship hold below the deck of the ship uninsulated and to insulate the surface of the hold. Thus, as shown in FIG. 2, the bottom of the hold is covered by insulation 60 and the internal wall of the hold is covered by insulation 61. Of course, if it is desirable, it is also within the scope of the invention to insulate the external surface of the tank 11 even though the ship hold is insulated.

Another embodiment of the invention is shown in FIGS. 6 and 7. This embodiment of the invention is particularly useful when insulation 63 is placed against the outside surface of the wall of tank 11 and when the walls of the ship hold are left free of insulation. Those elements and parts present in the embodiment shown in FIGS. 6 and 7 which are common to the earlier embodiment described with reference to FIGS. 4 and 5 will be identified by the same numbers for convenience.

As shown in FIGS. 6 and 7, insulating block 65 is secured between four metal angles 66, 67, 68 and 69 which are joined to plate 20. Metal plate 70is joined to the front of insulating block 65 by means of bolts 78.

In a like manner, insulating block 71 is secured in place between angle irons 72, 73, 74 and 75 which are joined to plate 19. The front of insulating block 71 has a metal plate 76 held in place thereon by means of bolts 77. The insulating blocks 65 and 71 together constitute a support key unit. The face 80 of plate 70 is vertically positioned and constitutes a key contact face. Simi' larly, face 81 of metal plate 76 is vertically positioned and constitutes a key contact face. The key contact faces 80 and 81 are each positioned at an acute angle X to a radius from the tank center to a mid-point Z which is located between the two key contact faces 80 and 81.

' Metal plate is secured in a bracket composed of top plate 91, bottom plate 92 and side plates 93 and 94 which are joined to plate 95 mounted on wall 34. Bolts 96 secure plate 90 in position and adjusting bolt 97 functions to position plate 90 in face to face contact with plate 70. The front face 98 of plate 90 constitutes a block contact face which is vertically positioned at an acute angle X to the radius from the tank center to the midpoint Z between the block contact faces 98 and 109. The angle of the block contact face is of course the same as the angle of the mating contact face.

Chocking material 99 is positioned between plate 90 and plate 95 after the block contact face 98 is positioned against the key contact face 80.

Plate 100 is mounted between top plate 101, bottom plate 102, and side plates 103 and 104 which are joined to plate 105 which is attached to wall 33.Bolts 106 hold plate 100 in position. Bolt 107 is used for adjusting plate 100 into contact with plate 76. After contact has been made between the plates, chocking material 108 is placed between plates 100 and 105. The front surface or face 109 of plate 100 constitutes a block contact face and it is vertically positioned to mate throughout itssurface with the key contact surface 81 of plate 76. Furthermore, the surface 109 is positioned at an acute angle X which is identical to the angle of key contact face 81.

The embodiments of the invention described herein provide a support system which can resist horizontal and vertical forces on the ship structure. In addition, the support system does not restrain temperature contraction and expansion of the tank shell produced by cargo loading and unloading. The blocks and keys when properly fitted form a spline capable of developing the reactive force. The horizontal force on the tank is transmitted through the shell to the keys by tangential shear having a sinusoidal distribution around the shell circumference. Similarly, the load transferred to the keys will have a sinusoidal distribution. The keys located at 90 to the direction of the force will experience the maximum shear load. Those at 0 will transfer no load. By transferring load in this manner the bending moments produced in the shell and horizontal supports are minimized. The slope of the interfaces between the tank support keys and the ship block supports is such that radial movement produced by changes in the tank shell temperature can occur without loss of contact or binding along the interface. Furthermore, the interfaces permit vertical movement of the tank with respect to the ship without loss of contact at the interface.

Although the specific embodiments of the invention disclosed herein show insulation as part of the support keys or the support blocks, it should be understood that for some uses such insulation can be replaced by noninsulating load bearing material.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

What is claimed is:

1. In a ship having a cargo tank, with a circular horizontal cross section, which expands and contracts in service, supported in a hold therein, the improved tank support system comprising:

tank restraining means providing both vertical upward and horizontal lateral support and including a plurality of support columns depending downwardly from the tank and providing primarily vertical support to said tank, and further, said tank re straining means including a plurality of both support keys attached to the side of the tank and support blocks attached in the ship hold and adapted to receive the associated tank mounted support key thereby primarily restraining the tank from horizontal movement induced from sea conditions yet allowing thermal expansion and contraction of the tank,

each of said support keys having a pair of opposing spaced-apart vertical key contact faces extending in a plane forming an acute angle with a radius extending from the cargo tank center to a midpoint between the spaced-apart key contact faces,

said plurality of spaced-apart support blocks joined by connecting means to the ship hold, said support blocks being located around the periphery of the tank with a support block opposite each support key, and

each support block having a pair of opposing spacedapart vertical block contact faces positioned at the same acute angle as the key contact faces and positioned to have a block contact face in mating contact with a key contact face,

whereby upon expansion and contraction of the tank with temperature change uniform horizontal slidable support contact is maintained between mating key contact and block contact faces.

2. A tank support system according to claim 1 in which the key contact faces are insulated from the tank wall.

3. A tank support system according to claim 1 in which the tank has an insulated substantially spherical bottom positioned in a hold of the ship.

4. A tank support system according to claim 1 in which the block contact faces are insulated from the ship hold.

5. A tank support system according to claim 1 in which the tank has a substantially spherical bottom positioned in an insulated hold of the ship.

6. A tank support system according to claim 1 in which the connecting means joining the support blocks to the ship hold is a plurality of columns, with each column having a support block thereon.

7. A tank support system according to claim 1 in which each key contact face is slidable vertically with the mating block contact face.

8. A tank support system according to claim 1 and said tank support means including a horizontally disposed reinforcing ring extending about and attached to said cargo tank, and said support means also including vertically upwardly extending portions attached to both the tank and to said reinforcing ring, and each of said columns of the tank support means .includes a plurality of downwardly extending beam means depending from said reinforcing ring and aligned with associated vertically upwardly extending portions.

9. A tank support system according to claim 1 in which the ship hold mounted support blocks include adjusting members connected thereto and to the ship hold thereby providing for adjusting movement of said support blocks into and from engagement with the associated key contact face.

10. In a ship having a cargo tank with a circular horizontal cross section which undergoes thermal expansion and contraction during transport in said ship, an improved tank support system including:

aplurality of tank restraining keys attached around the side periphery of the tank and each key having a pair of spaced key contact surfaces arranged in vertical planes diverging outwardly of said tank, and further, said tank support system including a plurality of spaced-apart support blocks joined by a mounting and connecting means to said ship hold and said support blocks having contact faces adapted to receive the associated tank mounted key contact surface whereby the restraining key and the associated support blocks provide primarily horizontal restraint to the tank to prevent horizontal tank movement from external forces yet permitting thermal expansion and contraction of the tank in a horizontal plane, and

a plurality of tank support columns mounted adjacent the tank restraining key and providing primarily'vertical support to said tank,

support block adjusting means movably positioned within the ship hold connecting means and having attaching portions joined with said support blocks thereby providing for adjusting reciprocating movement of each support block contact face into and from engagement with an associated key contact face.

11. A tank support system according to claim 10 in which thermal insulating blocks are positioned between the tank and the ship connecting means, and said insulating blocks having portions mounted adjacent each tank support key and each associated support block.

12. A tank support system according to claim 10 in which each support block includes portions spaced from the attached ship hold connecting means thereby defining a cavity;

a chock member being positioned within said cavity and having portions in binding contact with both zontal cross section, which expands and contracts inservice, supported therein, the improved tank support system comprising:

tank support means attached to and located around the periphery of said cargo tank and including a;

plurality of columns for imparting vertical support to said tank, and said tank support means also including circumferentially spaced-apart support keys adapted to provide horizontal restraint to said I cargo tank,

each of said support keys having a pair of opposing spaced-apart vertical key contact faces extending in a plane forming an acute angle with a radius extending from the cargo tank center to a midpoint between the spaced-apart key contact faces,

a plurality of spaced-apart support blocks joined by connecting means to a ship hold, said support blocks being located around the periphery of the tank with a support block opposite each support key, and

each support block having a pair of opposing spacedapart vertical block contact faces positioned at the same acute angle as the key contact faces and positioned to have a block contact face in mating contact with a key contact face,

whereby upon expansion and contraction of the tank with temperature change uniform horizontal slidable support contact is maintained between mating key contact and block contact faces; and, said tank support system including a horizontally disposed reinforcing ring extending about and at tached to said cargo tank, and said support means, also including vertically upwardly extending portions attached to both the tank and to said reinforcing ring, and each of said columns of the tank sup- 8 port means includes a plurality of downwardly extending beam means depending from said reinforcing ring and aligned with associated vertically upwardly extending portions. 14. In a ship having a cargo tank with a circular horizontal cross section which undergoes thermal expansion and contraction during transport in said ship, an

improved tank support system including:

a plurality of spaced tank support keys mounted on said tank and each key having a pair of spaced key contact surfaces arranged in planes diverging outwardly of said tank,

a plurality of spaced-apart support blocks joined by connecting means to said ship hold and said support blocks being positioned to receive an associated tank support key,

each support block having a pair of opposing spacedapart block contact faces positioned for mating contact with the associated key contact faces,

support block adjusting means movably positioned within the ship hold connecting means and having attaching portions joined with said support blocks thereby providing for adjusting reciprocating; movement of each support block contact face into and from engagement with an associated key contact face; and,

said tank support system including a horizontally dis-I posed reinforcing ring extending about and at-@ tached to said cargo tank, and said support system i also including vertically upwardly extending por tions attached to both the tank and to said reinforcing ring, and said tank support system includes with associated vertically upwardly extending 

1. In a ship having a cargo tank, with a circular horizontal cross section, which expands and contracts in service, supported in a hold therein, the improved tank support system comprising: tank restraining means providing both vertical upward and horizontal lateral support and including a plurality of support columns depending downwardly from the tank and providing primarily vertical support to said tank, and further, said tank restraining means including a plurality of both support keys attached to the side of the tank and support blocks attached in the ship hold and adapted to receive the associated tank mounted support key thereby primarily restraining the tank from horizontal movement induced from sea conditions yet allowing thermal expansion and contraction of the tank, each of said support keys having a pair of opposing spaced-apart vertical key contact faces extending in a plane forming an acute angle with a radius extending from the cargo tank center to a midpoint between the spaced-apart key contact faces, said plurality of spaced-apart support blocks joined by connecting means to the ship hold, said support blocks being located around the periphery of the tank with a support block opposite each support key, and each support block having a pair of opposing spaced-apart vertical block contact faces positioned at the same acute angle as the key contact faces and positioned to have a block contact face in mating contact with a key contact face, whereby upon expansion and contraction of the tank with temperature change uniform horizontal slidable support contact is maintained between mating key contact and block contact faces.
 2. A tank support system according to claim 1 in which the key contact faces are insulated from the tank wall.
 3. A tank support system according to claim 1 in which the tank has an insulated substantially spherical bottom positioned in a hold of the ship.
 4. A tank support system according to claim 1 in which the block contact faces are insulated from the ship hold.
 5. A tank support system according to claim 1 in which the tank has a substantially spherical bottom positioned in an insulated hold of the ship.
 6. A tank support system according to claim 1 in which the connecting means joining the support blocks to the ship hold is a plurality of columns, with each column having a support block thereon.
 7. A tank support system according to claim 1 in which each key contact face is slidable vertically with the mating block contact face.
 8. A tank support system according to claim 1 and said tank support means including a horizontally disposed reinforcing ring extending about and attached to said cargo tank, and said support means also including vertically upwardly extending portions attached to both the tank and to said reinforcing ring, and each of said columns of the tank support means includes a plurality of downwardly extending beam means depending from said reinforcing ring and aligned with associated vertically upwardly extending portions.
 9. A tank support system according to claim 1 in which the ship hold mounted support blocks include adjusting members connected thereto and to the ship hold thereby providing for adjusting movement of said support blocks into and from engagement witH the associated key contact face.
 10. In a ship having a cargo tank with a circular horizontal cross section which undergoes thermal expansion and contraction during transport in said ship, an improved tank support system including: a plurality of tank restraining keys attached around the side periphery of the tank and each key having a pair of spaced key contact surfaces arranged in vertical planes diverging outwardly of said tank, and further, said tank support system including a plurality of spaced-apart support blocks joined by a mounting and connecting means to said ship hold and said support blocks having contact faces adapted to receive the associated tank mounted key contact surface whereby the restraining key and the associated support blocks provide primarily horizontal restraint to the tank to prevent horizontal tank movement from external forces yet permitting thermal expansion and contraction of the tank in a horizontal plane, and a plurality of tank support columns mounted adjacent the tank restraining key and providing primarily vertical support to said tank, support block adjusting means movably positioned within the ship hold connecting means and having attaching portions joined with said support blocks thereby providing for adjusting reciprocating movement of each support block contact face into and from engagement with an associated key contact face.
 11. A tank support system according to claim 10 in which thermal insulating blocks are positioned between the tank and the ship connecting means, and said insulating blocks having portions mounted adjacent each tank support key and each associated support block.
 12. A tank support system according to claim 10 in which each support block includes portions spaced from the attached ship hold connecting means thereby defining a cavity; a chock member being positioned within said cavity and having portions in binding contact with both the ship connecting means and the adjacent support block portion.
 13. In a ship having a cargo tank, with a circular horizontal cross section, which expands and contracts in service, supported therein, the improved tank support system comprising: tank support means attached to and located around the periphery of said cargo tank and including a plurality of columns for imparting vertical support to said tank, and said tank support means also including circumferentially spaced-apart support keys adapted to provide horizontal restraint to said cargo tank, each of said support keys having a pair of opposing spaced-apart vertical key contact faces extending in a plane forming an acute angle with a radius extending from the cargo tank center to a midpoint between the spaced-apart key contact faces, a plurality of spaced-apart support blocks joined by connecting means to a ship hold, said support blocks being located around the periphery of the tank with a support block opposite each support key, and each support block having a pair of opposing spaced-apart vertical block contact faces positioned at the same acute angle as the key contact faces and positioned to have a block contact face in mating contact with a key contact face, whereby upon expansion and contraction of the tank with temperature change uniform horizontal slidable support contact is maintained between mating key contact and block contact faces; and, said tank support system including a horizontally disposed reinforcing ring extending about and attached to said cargo tank, and said support means also including vertically upwardly extending portions attached to both the tank and to said reinforcing ring, and each of said columns of the tank support means includes a plurality of downwardly extending beam means depending from said reinforcing ring and aligned with associated vertically upwardly extending portions.
 14. In a ship having a cargo tank with a circular horizontal cross section which undergoes thermal expansion and contraction during transport in said ship, an Improved tank support system including: a plurality of spaced tank support keys mounted on said tank and each key having a pair of spaced key contact surfaces arranged in planes diverging outwardly of said tank, a plurality of spaced-apart support blocks joined by connecting means to said ship hold and said support blocks being positioned to receive an associated tank support key, each support block having a pair of opposing spaced-apart block contact faces positioned for mating contact with the associated key contact faces, support block adjusting means movably positioned within the ship hold connecting means and having attaching portions joined with said support blocks thereby providing for adjusting reciprocating movement of each support block contact face into and from engagement with an associated key contact face; and, said tank support system including a horizontally disposed reinforcing ring extending about and attached to said cargo tank, and said support means also including vertically upwardly extending portions attached to both the tank and to said reinforcing ring, and each of said columns of the tank support means includes a plurality of downwardly extending beam means depending from said reinforcing ring and aligned with associated vertically upwardly extending portions. 